Pythium insidiosum: Diagnosis and Treatment

Pythium insidiosum: Diagnosis and Treatment

Robert L. GlassPan American Veterinary Laboratories

Robert L. GlassPan American Veterinary Laboratories

Pythium insidiosumPythium insidiosum

Kingdom Stramenipila Kingdom Stramenipila

Oomycete “aquatic fungus” Oomycete “aquatic fungus”

Hyphal elements similar to Fungi Hyphal elements similar to Fungi

Primarily an infectious agent of plants Primarily an infectious agent of plants

PythiosisPythiosis

PhycomycosisPhycomycosis

Florida Horse LeechesFlorida Horse Leeches

Swamp CancerSwamp Cancer

Species Infected bySpecies Infected by Pythium insidiosum Pythium insidiosumCanineCanine Australia, Brazil, Korea, USA and VenezuelaAustralia, Brazil, Korea, USA and Venezuela

EquineEquine Australia, Brazil, Colombia, Costa Rica, New Zealand, Australia, Brazil, Colombia, Costa Rica, New Zealand, New Guinea, USA and VenezuelaNew Guinea, USA and Venezuela

FelineFeline USAUSA

Bovine Bovine Brazil, USA and VenezuelaBrazil, USA and Venezuela

HumanHuman Australia, New Zealand, Haiti, India ThailandAustralia, New Zealand, Haiti, India Thailand and the USAand the USA

Bear Bear USAUSA

Camel Camel USAUSA

Incidence of Pythiosis in the USIncidence of Pythiosis in the US

1995-2003 158 cases (all species)2004 72 cases (all species)2005 (Jan-Aug) 102 cases (all species)2010 752 cases (all species)

EpidemiologyEpidemiology

OosporeOospore

Life CycleLife Cycle

Skin

SkinSkininjuryinjury

Skin

PythiosisPythiosisPythiosisPythiosis

ClinicalClinical Characteristics of pythiosisCharacteristics of pythiosis

- Cutaneous Cutaneous Keratinitis Keratinitis

NecrosisNecrosis- SubcutaneousSubcutaneous LymphaticLymphatic

PeriorbitalPeriorbital

- Arterial Arterial Large arteriesLarge arteries AneurysmAneurysm

- Intestinal Intestinal Intestinal tractIntestinal tract

- SystemicSystemic LiverLiver

LungsLungs

FelineFeline PythiosisPythiosis

CanineCanine PythiosisPythiosis

Intestinal pythiosis in canines is often misdiagnosed as lymphoma.

Bovine PythiosisBovine Pythiosis Venezuela Venezuela

EquineEquine PythiosisPythiosis

““kunkers”kunkers”

Chronic PythiosisChronic Pythiosis Osteo infectionOsteo infection

Human pythiosis in the USAHuman pythiosis in the USA

Tennessee 1998Tennessee 1998 Texas 1989Texas 1989

Human Pythiosis, ThailandHuman Pythiosis, Thailand

IgGIgGIgMIgM

PythiosisExperimental

PythiosisExperimental

Laboratory DiagnosisLaboratory Diagnosis

1) Very few laboratories are familiar with P. Insidiosum

2) Difficult to culture

3) Difficult to identify in histopath studies

4) Difficult to identify by clinical presentation

1) Very few laboratories are familiar with P. Insidiosum

2) Difficult to culture

3) Difficult to identify in histopath studies

4) Difficult to identify by clinical presentation

Conidiobolus coronatusConidiobolus coronatus Basidiobolus ranarum Basidiobolus ranarum Fungal zygomycetesFungal zygomycetes

Pythium insidiosumPythium insidiosum OomyceteOomycete

Differential DiagnosisDifferential Diagnosis

Wet mountWet mount10% KOH10% KOHWet mountWet mount10% KOH10% KOH Immune-fluorescenceImmune-fluorescenceImmune-fluorescenceImmune-fluorescence

CultureCultureCultureCultureHistopathologyHistopathologyHistopathologyHistopathology

immunoperoxidaseimmunoperoxidaseimmunoperoxidaseimmunoperoxidase

Tissue Biopsy Studies

Serologic DiagnosisSerologic DiagnosisAgar Gel Immunodiffusion

Western Blot

Classical treatments usedagainst Pythium insidiosumClassical treatments usedagainst Pythium insidiosum

Surgery ~40%

Iodines ~35-40%

Amphotericine B <30%Itraconazole <30%

Surgery ~40%

Iodines ~35-40%

Amphotericine B <30%Itraconazole <30%

What is Pythium Immunotherapy?What is Pythium Immunotherapy?

Allergy desensitization via Subcutaneous presentation of purified P. insidiosum antigens Allergy desensitization via Subcutaneous presentation of purified P. insidiosum antigens

Switching of the of the immune response from TH2 (allergic) to TH1 mode (protective and curative)

ImmunotherapyImmunotherapy

T helper 2 responseT helper 2 response

EosinophilsEosinophils Mast cellsMast cells IgEIgE IL5IL5 IL4IL4

T helper 1 responseT helper 1 response

MacrophagesMacrophages T lymphocytesT lymphocytes (cytotoxic?)(cytotoxic?) IFNIFN IL2IL2

ImmunotherapyImmunotherapy

Pythium Infection

Infection Cleared

Before ImmunotherapyBefore Immunotherapy Day 4 Day 4 Day 8 Day 8 Day 15 Day 15

Pythium antibody in Canines participating in Field Pythium antibody in Canines participating in Field Trial Training and CompetitionsTrial Training and Competitions

Result #Dogs % of TotalResult #Dogs % of Total

Negative 105 61.4 Negative 105 61.4

Borderline 43 25.1Borderline 43 25.1

Positive Positive 23 13.5 23 13.5

Total 171 100 Total 171 100

* Normal Dogs <1 % Positive ,<5% Borderline, >95% Negative* Normal Dogs <1 % Positive ,<5% Borderline, >95% Negative

Pythium Associated Symptoms in Field Trial/Hunt Pythium Associated Symptoms in Field Trial/Hunt CaninesCanines

VOMITING/DIARRHEAVOMITING/DIARRHEA IN LAST 12 MONTHSIN LAST 12 MONTHS

Blood testBlood test

Negative 7 (6.7%)Negative 7 (6.7%)

Borderline 3 (7.0%)Borderline 3 (7.0%)

Positive 13 (26.1%) Positive 13 (26.1%)

Efficacy of Pythium Immunotherapy

Studies Conducted 2004-2005Studies Conducted 2004-2005

Species # Treated # Successes # Failures %Success

Equine 58 52 6 90%

Canine 28 15 13 53%

Bovines 65 65 0 100%

Efficacy of Pythium V2 ImmunotherapyIn Canines

Studies Conducted 2007-2008Studies Conducted 2007-2008

# Treated # Successes # Failures %Success

14 10 4 71%

ImmunotherapyImmunotherapy

BeforeBefore

AfterAfter

BeforeBefore

AfterAfter

TreatmentRegimen

1cc Sub Q

Day 1 Day 7 Day 21

8/22/03 9/27/03

11/25/033/17/04

Immunotherapy

Treatment

Progression

Surgery + ImmunotherapySurgery + Immunotherapy

Immunotherapy

Purified protein extract of P. insidiosum

Early treatment increases success rate

Use as first option treatment

>85% effective in equines, 50% effective in canines

Combine with surgical de bulking in chronic cases

Pythium insidiosum is endemic in tropical and subtropical regions

Differential diagnosis includes subcutaneous mycosis, lymphoma, parasitic and bacterial infections Serologic diagnosis is fast and accurate

Itraconazole, Amphotericin B, Iodine and surgery have shown limited success

Immunotherapy alone or in conjunction with other therapies demonstrates highest success rate

Pythium insidiosum is endemic in tropical and subtropical regions

Differential diagnosis includes subcutaneous mycosis, lymphoma, parasitic and bacterial infections Serologic diagnosis is fast and accurate

Itraconazole, Amphotericin B, Iodine and surgery have shown limited success

Immunotherapy alone or in conjunction with other therapies demonstrates highest success rate

Lagenidium gigantumLagenidium gigantum

Similar to Pythium in classSimilar to Pythium in class

Similar to Pythium in disease Similar to Pythium in disease characteristicscharacteristics

Essentially identical to Pythium in Essentially identical to Pythium in tissue sectionstissue sections

Does not respond to Pythium Does not respond to Pythium ImmunotherapyImmunotherapy

Accurate Diagnosis is Essential Accurate Diagnosis is Essential

Clinical presentation is not good Clinical presentation is not good enoughenough

Histopath examination is not good Histopath examination is not good enoughenough

Pythium test alone is not good enoughPythium test alone is not good enough

Accurate diagnosis requires blood test Accurate diagnosis requires blood test for both Pythium and Lagenidiumfor both Pythium and Lagenidium